Recently, ink jet printing technology has been used for presentation, graphic arts, engineering drawing and home office applications. The performance requirements for ink jet recording media used for these applications are quite stringent. The media should provide fast drying, good color fidelity, high image resolution, and archivability. For transparency applications, curl performance on various commercial projectors is also important. There are many commercial products and proposed designs available in the field. Among them, oxazoline-based polymeric ink sorptive coatings have shown promising performance, even though only a limited amount of effort was previously expended by those skilled in the art exploring this type of chemistry for ink jet applications. As a result, only a limited amount of information on this subject is available in the prior art, or was otherwise available to the present inventors prior to their present inventive discovery.
U.S. Pat. No. 4,889,765 discloses an ink-receptive coating composition comprising a polymer of 2-oxazoline, preferably polyethyl oxazoline, and an olefin copolymer containing pendant acid groups which are substantially neutralized by a base. U.S. Pat. No. 5,389,723 discloses coatings formed from semi-interpenetrating polymeric networks comprising a blend of a polymeric matrix component, a liquid absorbent component, and a poly-functional aziridine crosslinking agent for forming water-durable networks. A polyethyl oxazoline is mentioned as a possible liquid absorbent material.
U.S. Pat. No. 4,956,230 discloses coatings containing (1) a hydrophilic polymer containing a carbonylamido group and (2) a hydrophobic polymer without acidic, hydroxyl, .dbd.NH and --NH.sub.2 functional groups.
The above designs differ from the design of the recording media of the present invention, and the ink sorptive coatings used therein, in both concept and compositions. For example, the present inventive design does not require acidic functional groups containing polyolefin copolymers and aziridine crosslinking agents. Instead, in the present invention, hydrogels are formed through inherent physical and chemical interactions. Furthermore, we have found that the present inventive design provides optimal performance by using hydrophilic polymers containing acidic, hydroxyl, .dbd.NH and --NH.sub.2 functional groups, especially hydroxyl groups, in the polyalkyl- or polyphenyl-oxazoline based ink sorptive coatings of the present invention. That is, we have discovered that such functional groups can be helpful in designing ink jet media containing hydrophilic alkyl and phenyl oxazoline-based polymeric ink sorptive coatings.